What is the mechanism by which the "invisible hand" pushes markets to equilibrium? describe the two main causes of market failure and give an ex of each. Use a production possibilities frontier to describe efficiency. (This problem can be answered either with or without the use of a graph, depending on whether you have a graphing program on your computer. It is possible to describe the various points on the PPF without a graph.). What is the difference between a positive and a normative statement? Give an ex of each. describe how absolute advantage differs from comparative advantage. What are the factors that determine the quantity of a good that buyers demand? Define the equilibrium of a market. Describe the forces that move a market toward its equilibrium. List and describe the four determinants of price elasticity of demand.